Endoscope and manufacturing method therefor

ABSTRACT

An endoscope is provided with a pliable tube having an integument layer made of a resin constituting an insertion portion and at least one slender tube element inserted through the insertion portion. The amount of contraction of the pliable tube after application of a thermal load during a high-pressure steam sterilization step is set larger than the amount of contraction of the tube element after application of a thermal load during the high-pressure steam sterilization step.

[0001] This application claims benefit of Japanese Application No.2001-195131 filed on Jun. 27, 2001, the contents of which areincorporated by this reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to an endoscope including aflexible pliable tube in an insertion portion wherein at least oneslender tube element is installed in this pliable tube, and amanufacturing method therefor.

[0004] 2. Description of Related Art

[0005] Hitherto, medical endoscopes have been used widely, whereinorgans in body cavities, etc., can be observed by inserting slenderinsertion portions in the body cavities and, if necessary, varioustherapeutic treatments can be performed using endo-therapy productsinserted through endo-therapy product channels.

[0006] In particular, regarding the endoscope used in a medical field,by inserting the insertion portion in the body cavity, observation oforgans, etc., is performed and various therapies and treatments areperformed using endo-therapy products inserted through the endo-therapyproduct channel of the endoscope. Consequently, when an endoscope andendo-therapy product used once have been reused for other patients, ithas been necessary to perform cleaning and disinfection after aninspection and treatment has been completed for reasons of necessity toprevent cross infection between patients through the endoscope andendo-therapy product.

[0007] In recent years, inexpensive autoclave sterilization(high-pressure steam sterilization) has become the mainstream of thedisinfection and sterilization treatments of medical equipment, whereinno complicated operation attends, it is possible to use immediatelyafter sterilization, and a running cost is low.

[0008] Consequently, in Japanese Unexamined Patent ApplicationPublication No. 10-276968, an endoscope is disclosed, in which in orderthat a built-in tube does not contract during high-pressure steamsterilization with an autoclave and that an adequate sterilizationtreatment can be performed repeatedly, a tube made of fluororesin isused as a pliable tube built in for passing through a fluid,endo-therapy product, or the like, and the tube made of fluororesin issubjected to an annealing treatment before being incorporated into theendoscope.

[0009] However, the aforementioned tube is difficult to contractcompletely during the annealing treatment because of, for example,differences in material properties, such as thermal deformationtemperatures and glass transition temperatures, differences instructures, such as the material, which may be a solid material or foam,constituting the tube, and differences in manufacturing methods. Thatis, for example, some tubes do not contract unless very high temperatureis applied, and some tubes need long-duration annealing. Regarding thesetubes, even when the annealing treatment was performed at a temperatureslightly higher than that in the high-pressure steam sterilization step,sometimes, the tube shrank more than the condition desired because thehigh-pressure steam sterilization step was performed repeatedly over thelong term.

[0010] Furthermore, when the tube shrank more than the conditiondesired, it was feared that an excessive force was applied to theconnection portions at both ends of the tube and, therefore, breakagewas brought about, or the tube was pulled in the insertion portion and,therefore, inconvenience was brought about in the shape of a curve of acurved portion installed at the tip side of the insertion portion.

[0011] The present invention was made in consideration of theaforementioned circumstances. Accordingly, it is an object of thepresent invention to provide an endoscope in which inconvenience broughtabout due to contraction of a tube element built in an insertion portionduring high-pressure steam sterilization is prevented.

SUMMARY OF THE INVENTION

[0012] An endoscope according to the present invention is an endoscopeprovided with a pliable tube having an integument layer made of a resinconstituting an insertion portion and at least one slender tube elementwhich is inserted through the aforementioned insertion portion, whereinthe amount of contraction of the aforementioned pliable tube afterapplication of a thermal load during a high-pressure steam sterilizationstep is set larger than the amount of contraction of the aforementionedtube element after the application of the thermal load during thehigh-pressure steam sterilization step.

[0013] According to this configuration, when the tube element built inthe insertion portion contracts due to the thermal load during thehigh-pressure steam sterilization step, the pliable tube contracts by anamount equivalent to or more than the amount of contraction of the tubeelement at the same time and, therefore, the relationship in lengthbetween the tube element and the pliable tube, on which this tubeelement is fixed directly or indirectly, is similar to that in theinitial condition or there is a tendency of the tube element to sag.

[0014] The above and other objects, features and advantages of theinvention will become more clearly understood from the followingdescription referring to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a diagram for explaining the configuration of anendoscope apparatus according to an embodiment of the present invention.

[0016]FIG. 2 is a partial sectional view for explaining theconfiguration of a pliable tube according to an embodiment of thepresent invention.

[0017]FIG. 3 is a diagram for explaining built-in materials insertedthrough a pliable tube according to an embodiment of the presentinvention.

[0018]FIG. 4 is a diagram for explaining the installment conditions inan insertion portion of a tube element according to an embodiment of thepresent invention.

[0019]FIG. 5A and FIG. 5B are diagrams for explaining the amount ofcontraction of a tube element according to an embodiment of the presentinvention.

[0020]FIG. 5A is a diagram showing the condition of the tube in theinitial condition, and FIG. 5B is a diagram showing the condition of thetube after high-pressure steam sterilization.

[0021]FIG. 6A and FIG. 6B are diagrams for explaining the amount ofcontraction of a pliable tube according to an embodiment of the presentinvention.

[0022]FIG. 6A is a diagram showing the condition of the pliable tube inthe initial condition, and FIG. 6B is a diagram showing the condition ofthe pliable tube after high-pressure steam sterilization.

[0023]FIG. 7A, FIG. 7B, FIG. 7C, and FIG. 7D are diagrams for explaininga formation step of a pliable tube according to an embodiment of thepresent invention.

[0024]FIG. 7A is a diagram showing an assembly in which a helical tubeand a mesh-shaped tube in the natural length conditions are combined.FIG. 7B is a diagram showing the assembly extended by a predeterminedlength, FIG. 7C is a diagram showing the pliable tube formed by applyinga covering of integument layer to the extended assembly, and FIG. 7D isa diagram showing the pliable tube in the condition of being shrunkenafter high-pressure steam sterilization.

[0025]FIG. 8A, FIG. 8B, FIG. 8C, and FIG. 8D are diagrams for explaininganother formation step of a pliable tube according to an embodiment ofthe present invention.

[0026]FIG. 8A is a diagram showing an assembly in which a helical tubeand a mesh-shaped tube in the natural length conditions are combined,FIG. 8B is a diagram showing the assembly in the condition of beingprovided with an integument layer, FIG. 8C is a diagram showing thepliable tube formed by extending the assembly covered with theintegument layer, and FIG. 8D is a diagram showing the pliable tube inthe condition of being shrunken after high-pressure steam sterilization.

[0027]FIG. 9A and FIG. 9B are sectional views for explaining theconfiguration of a pliable tube according to an embodiment of thepresent invention.

[0028]FIG. 9A is a sectional view explaining a helical tube and amesh-shaped tube in the natural length conditions. FIG. 9B is asectional view explaining the pliable tube in the pliable tube formationconditions.

[0029]FIG. 10A and FIG. 10B are sectional views for explaining anotherconfiguration of a pliable tube according to an embodiment of thepresent invention.

[0030]FIG. 10A is a sectional view explaining a helical tube in thenatural length conditions. FIG. 10B is a sectional view explaining thepliable tube in the pliable tube formation conditions.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0031] The embodiments according to the present invention will bedescribed below with reference to the drawings.

[0032] The embodiments regarding endoscopes, in which inconveniencebrought about due to contraction of a tube element built in an insertionportion during high-pressure steam sterilization is prevented, will bedescribed.

[0033]FIG. 1 to FIG. 8D are diagrams for explaining endoscopes accordingto those embodiments. FIG. 1 is a diagram for explaining theconfiguration of an endoscope apparatus. FIG. 2 is a partial sectionalview for explaining the configuration of a pliable tube. FIG. 3 is adiagram for explaining built-in materials inserted through a pliabletube. FIG. 4 is a diagram for explaining the installment conditions inan insertion portion of a tube element. FIG. 5A and FIG. 5B are diagramsfor explaining the amount of contraction of a tube element. FIG. 6A andFIG. 6B are diagrams for explaining the amount of contraction of apliable tube. FIG. 7A to FIG. 7D are diagrams for explaining a formationstep of a pliable tube. FIG. 8A to FIG. 8D are diagrams for explaininganother formation step of a pliable tube.

[0034]FIG. 7A is a diagram showing an assembly in which a helical tubeand a mesh-shaped tube in the natural length conditions are combined.FIG. 7B is a diagram showing the assembly extended by a predeterminedlength. FIG. 7C is a diagram showing the pliable tube formed by applyinga covering of integument layer to the extended assembly. FIG. 7D is adiagram showing the pliable tube in the condition of being shrunkenafter high-pressure steam sterilization. FIG. 8A is a diagram showing anassembly in which a helical tube and a mesh-shaped tube in the naturallength conditions are combined. FIG. 8B is a diagram showing theassembly in the condition of being provided with an integument layer.FIG. 8C is a diagram showing the pliable tube formed by extending theassembly covered with the integument layer. FIG. 8D is a diagram showingthe pliable tube in the condition of being shrunken after high-pressuresteam sterilization.

[0035] As shown in FIG. 1, an endoscope apparatus 1 according to thepresent embodiment is primarily composed of an electronic endoscope(hereafter simply referred to as endoscope) 2 provided with an imagepickup device, light equipment 3 for supplying illumination light, avideo processor 5 which controls the image pickup device and whichtreats signals attained from the aforementioned image pickup device, anda monitor 6 connected to this video processor 5. Reference numeral 34denotes a container case for sterilization, described later, whichcontains this endoscope 2.

[0036] The aforementioned endoscope 2 is composed of a slender insertionportion 7 having pliability, a control portion 8 connected to the baseend portion of this insertion portion 7, and a universal cord 9 whichhas pliability and which extends from the side of this control portion8.

[0037] A connector 10, which is freely attached to or detached from theaforementioned light equipment 3, is installed at the end portion of theaforementioned universal cord 9. By connecting this connector 10 to thelight equipment 3, illumination light from a lamp, although not shown inthe drawing, provided on the light equipment 3 is transmitted through alight guide, although not shown in the drawing, of the endoscope 2 and,therefore, radiates an observation section.

[0038] A folding-preventing member 12 of the insertion portion, which iscomposed of an elastic member and which is for preventing tight turning,is installed at the joint portion of the aforementioned insertionportion 7 and the control portion 8. Likewise, a folding-preventingmember 13 of the control portion is installed at the joint portion ofthe aforementioned control portion 8 and the universal cord 9. Likewise,a folding-preventing member 14 of the connector is installed at thejoint portion of the universal cord 9 and the connector 10.

[0039] The slender insertion portion 7 having pliability of theaforementioned endoscope 2 is configured to install succeedingly a hardtip portion 17 provided with, for example, an observation window,illumination window, etc., although not shown in the drawing, at the tipsurface, a curved portion 16 in which a plurality of bending parts areconnected succeedingly and which is curved freely, and a pliable tube 15having pliability in that order from the tip side. The aforementionedcurved portion 16 is curved by operating appropriately a curve controlknob 30 installed on the control portion 8, and the tip surface of thetip portion 17 provided with the observation window, etc., can be faceda desired direction.

[0040] The aforementioned control portion 8 is provided with a gassupply and water supply operation button 28, a suction operation button29, a plurality of remote switches 31, and 31 for remotely controllingthe aforementioned video processor 5, and an endo-therapy productinsertion hole 32 communicating with an endo-therapy product channelinstalled in the insertion portion of the endoscope 2 in addition to theaforementioned curve control knob 30. The gas supply and water supplyoperation button 28 is a button for performing a gas supply operation orwater supply operation when a cleaning liquid or gas is ejected towardthe aforementioned observation window from a gas supply and water supplynozzle, although not shown in the drawing, installed on the tip surface.The suction operation button 29 is a button for performing a suctionoperation through a suction hole, although not shown in the drawing,installed on the tip surface.

[0041] An electric connector portion 11 is installed on the side portionof the aforementioned connector 10. A signal connector 4 of a signalcord connected to the aforementioned video processor 5 is connected tothe electric connector portion 11 while being free to attach or detach.By connecting this signal connector 4 to the video processor 5, theimage pickup device of the endoscope 2 is controlled and, in addition,by producing image signals from electric signals transmitted from thisimage pickup device, an endoscope observation image is displayed on thescreen of the aforementioned monitor 6. A vent hole, although not shownin the drawing, communicating the inside and outside of the endoscope 2is installed in the electric connector portion 11. Consequently, theelectric connector portion 11 of the endoscope 2 is configured in orderthat a waterproof cap 33 with a pressure control valve (hereafterabbreviated as waterproof cap) provided with the pressure control valve(not shown in the drawing) for blocking the aforementioned vent hole isfree to attach or detach.

[0042] This connector 10 is provided with a gas supply base 21 connectedto a gas supply source, although not shown in the drawing, built in thelight equipment 3 while being free to attach or detach, a base 23 forpressurizing a water supply tank 22 and a liquid supply base 24connected to the water supply tank, which is a liquid supply tank, whilebeing free to attach or detach, a suction base 25 connected to a suctionsource, although not shown in the drawing, in order to perform suctionfrom the aforementioned suction hole, and an injection base 26 connectedto a water supply device, although not shown in the drawing, in order toperform supply of water.

[0043] Furthermore, this connector 10 is provided with an earth terminalbase 27 in order to return a leakage current to a high-frequencytreatment apparatus, although not shown in the drawing, when thehigh-frequency leakage current is generated in the endoscope 2 duringperformance of the high-frequency treatment, etc.

[0044] The aforementioned endoscope 2 is configured to be capable ofundergoing high-pressure steam sterilization after being used for anobservation or a treatment and being cleaned. When this endoscope 2 issubjected to the high-pressure steam sterilization, the aforementionedwaterproof cap 33 is fitted to the electric connector portion 11.

[0045] When the aforementioned endoscope 2 is subjected to thehigh-pressure steam sterilization, this endoscope 2 is contained in acontainer case 34 for sterilization. This container case 34 forsterilization is composed of a tray 35, which is a case body, and acover member 36. This tray 35 is provided with a regulation membercorresponding to the shape of the endoscope, although not shown in thedrawing, in order that each of the insertion portion 7, control portion8, universal cord 9, connector 10, etc., of the endoscope 2 is locatedat a predetermined position.

[0046] A plurality of vent holes for introducing high-pressure steam areformed in these tray 35 and cover member 36.

[0047] As shown in FIG. 2, a helical tube 37 which constitutes theinnermost layer and which is formed by helically winding a thinband-shaped piece of metal, a mesh-shaped tube 38, and a integumentlayer 39 integrally installed covering the outer perimeter of thismesh-shaped tube 38 are laminated and, therefore, the aforementionedpliable tube 15 is formed. The mesh-shaped tube 38 is formed into theshape of a tube by knitting a thin metal wire, knitting a thin non-metalwire, or knitting them, each being installed covering the outerperimeter of this helical tube 37. The aforementioned integument layer39 is formed from a resin material, for example, a thermoplasticelastomer.

[0048] As shown in FIG. 3, a plurality of slender built-in materials areinserted through the insertion portion 7 including the aforementionedpliable tube 15. These built-in materials includes curve control wires40 which are made of a metal and which are moved forward or backward bythe operation of the aforementioned curve control knob 30 in order tobring about curving action of the aforementioned curved portion 16 in,for example, the vertical or horizontal direction, a wire-covered coil41 which is made of a metal and which covers these curve control wires40 in the condition of being inserted movably, a light guide 42 made ofan optical fiber bundle for supplying illumination light, a gas supplytube 43 and a water supply tube 44 which are tube elements fortransporting fluids and which are formed from PTFE, etc., a channel tubefor inserting a endo-therapy product (hereafter referred to asendo-therapy product tube) 45 which serves as a channel for insertingthe endo-therapy product and also serves as a suction pipeline of thefluids, a plurality of electric cables 46, and the like.

[0049] The aforementioned gas supply tube 43, water supply tube 44, andendo-therapy product tube 45 are fixed to, for example, connection pipes18 described below, which are connection portions installed individuallyat the control portion 8 and the tip portion 17 connected succeedinglyto both ends of the insertion portion 7.

[0050] As shown in FIG. 4, for example, one end of the aforementionedendo-therapy product tube 45 is connected and is fixed to the connectionpipe 18 fixed to the tip portion 17. On the other hand, the other end ofthe aforementioned endo-therapy product tube 45 is connected and isfixed to a branch member 19 having the aforementioned endo-therapyproduct insertion hole 32.

[0051] The aforementioned branch member 19 is fixed integrally to abase, although not shown in the drawing, installed at the base end ofthe pliable tube 15 with the control portion 8 therebetween. Theaforementioned tip portion 17 is fixed integrally to a base, althoughnot shown in the drawing, installed at the tip of the pliable tube 15with the aforementioned curved portion 16 therebetween.

[0052] Under this fixing condition, for example, when the aforementionedendo-therapy product tube 45 contracts, a force which brings about thecurving action of the aforementioned curved portion 16 in any directionis effected through the tip portion 17. According to this, inconvenienceoccurs in that the curved portion 16 is curved in an unintendeddirection, the amount of control force required for the curvingoperation is increased, and the like.

[0053]FIG. 5A is a diagram showing the condition of a tube in theinitial condition, and FIG. 5B is a diagram showing the condition of thetube after high-pressure steam sterilization. As shown in FIG. 5B, whenthe endoscope 2 is subjected to high-pressure steam sterilizationrepeatedly, the lengths of the aforementioned gas supply tube 43, watersupply tube 44, and endo-therapy product tube 45 become L2 becausecontraction occurs individually in the longitudinal direction comparedwith the length L1 in the initial condition due to thermal loads duringthis high-pressure steam sterilization. These amounts of contraction ofthe gas supply tube 43, water supply tube 44, and endo-therapy producttube 45 are X1, X2, and X3, respectively.

[0054] The aforementioned amounts of contraction are brought aboutbecause in manufacture, the aforementioned tubes 43, 44, and 45 aremolded under the condition of being pulled during molding, for example,extruding, and because these tubes 43, 44, and 45 become in thecondition of being able to deform by thermal loads and, therefore,stresses are released.

[0055] In consideration of these, regarding the pliable tube 15according to the present embodiment, the amount of contraction when athermal load is applied during the step of high-pressure steamsterilization is set larger than the amount of contraction of theaforementioned gas supply tube 43, water supply tube 44, andendo-therapy product tube 45.

[0056] Herein, the length of the pliable tube 15 is assumed to changefrom the length L1 in the initial condition to the length L2 after thehigh-pressure steam sterilization, and the amount of contraction of thepliable tube 15 due to the thermal load of the high-pressure steamsterilization is assumed to be Y as shown in FIG. 6B. Then, thefollowing relationships are set between this Y and the aforementionedX1, X2, and X3.

Y≧X1, Y≧X2, and Y≧X3

[0057] In order to set these relationships between the aforementionedpliable tube 15 and the tubes 43, 44, and 45, a thermal load of thehigh-pressure steam sterilization is applied to the aforementioned tubes43, 44, and 45, and amounts of contraction X1, X2, and X3 are measuredand determined by calculation in advance. Subsequently, the pliable tube15 is formed in order that the amount of contraction Y of theaforementioned pliable tube 15 becomes greater than the amounts ofcontraction X1, X2, and X3 of those tubes 43, 44, and 45.

[0058] Herein, the formation step of the pliable tube 15 will bedescribed.

[0059] The resin material for forming the integument layer 39 of theaforementioned pliable tube 15 is selected in consideration of usageconditions, for example, durability, insertion property into the bodycavity, etc., during use, and resistance against agents, etc., used forcleaning and disinfection. In the present embodiment, when the resinmaterial for forming the aforementioned integument layer 39 is selected,in addition to the aforementioned usage conditions, the one having sucha thermal deformation temperature that deformation is brought about by athermal load during high-pressure steam sterilization is selected.Herein, a temperature, at which a resin can be deformed by a thermalload during high-pressure steam sterilization, is defined as a thermaldeformation temperature H for the sake of convenience.

[0060] When the resin material for the integument layer 39 is selected,since the upper limit of the temperature during a general high-pressuresteam sterilization step is on the order of 140° C., the integumentlayer 39 is formed from, for example, the one primarily containingester-based thermoplastic elastomer which is a resin material satisfyingH≦140° C.

[0061] On the other hand, regarding the helical tube 37 and themesh-shaped tube 38 constituting the aforementioned pliable tube 15,assembling is performed in the pliable tube formation conditions inwhich these helical tube 37 and mesh-shaped tube 38 are brought about inthe condition of being extended compared with being in the naturallength conditions.

[0062] That is, as shown in FIG. 7A, an assembly 50 is formed in whichthe helical tube 37 and mesh-shaped tube 38 are combined. As shown inFIG. 7B, a tensile force is applied to this assembly 50 in the axisdirection and, therefore, the assembly 50 a extended by a length Zcompared with being in the natural length conditions is formed. At thistime, the length Z is an amount satisfying the condition that the amountof contraction Y of the pliable tube 15 during high-pressure steamsterilization ≧X1 (≧X2, ≧X3), and is the value larger than at least Y.

[0063] As shown in FIG. 7C, a molten resin for forming the integumentlayer 39 is extruded while the extended assembly 50 a is a core materialand, therefore, this assembly 50 a is covered with the resin.Subsequently, the resin is held until curing is completed. By curing theresin, a desired pliable tube 15 is formed in which the assembly 50extended by Z compared with being in the natural length conditions iscovered with the integument layer 39.

[0064] Regarding the step later than that shown in FIG. 7B, the pliabletube 15 may be formed by applying a covering of the tube element made ofthe resin which becomes the integument layer 39 to the assembly 50 a ofthe aforementioned helical tube 37 and mesh-shaped tube 38.

[0065] Furthermore, when a covering of the integument layer 39 isapplied, the assembly 50 composed of the aforementioned helical tube 37and mesh-shaped tube 38 may be kept in the condition of being extendedby a predetermined amount compared with being in the natural lengthconditions by applying a tensile force in the axis direction, a coveringof the integument layer 39 may be applied by extrusion and, therefore,the pliable tube 15 may be formed.

[0066] As the resin constituting the aforementioned integument layer 39,it is better to select a resin satisfying the usage conditions from anamide-based thermoplastic elastomer, styrene-based resin, fluorine-basedrubber, silicon-based rubber or a resin material made by blending them.

[0067] Regarding the pliable tube 15, gas supply tube 43, water supplytube 44, and endo-therapy product tube 45, speeds of contraction mayvary depending on the materials, structures, and manufacturing methodstherefor. Consequently, it is desirable that regarding the pliable tube15, gas supply tube 43, water supply tube 44, and endo-therapy producttube 45, respective initial dimensions, materials, structures, andmanufacturing methods are selected based on the amounts of contractionwhen loads are applied up to the endurance examples limit of theendoscope 2 against high-pressure steam sterilization.

[0068] In the present embodiment, only the pliable tube 15 constitutingthe insertion portion 7 is described. However, similar configuration maybe adopted regarding the pliable tube constituting the universal cord 9and a gas supply tube, water supply tube, and suction tube, although notshown in the drawing, installed therein.

[0069] Actions when the endoscope 2 configured as described above issubjected to high-pressure steam sterilization will be described.

[0070] First, typical conditions for high-pressure steam sterilizationwill be described.

[0071] Regarding the typical conditions, in the U.S. standard ANSI/AAMIST37-1992 approved by American National Standards Institute and issuedby Association for the Advancement of Medical Instrumentation, thesterilization step is specified to be at 132° C. for 4 minutes inprevacuum type, and the sterilization step is specified to be at 132° C.for 10 minutes in gravity type.

[0072] Although the temperature condition during the sterilization stepof high-pressure steam sterilization varies depending on the form ofhigh-pressure steam sterilization apparatuses and the time of thesterilization step, in general, it is set within the range on the orderof 115° C. to 138° C. Some sterilization apparatuses can be set at onthe order of 142° C.

[0073] The time condition varies depending on the temperature conditionduring the sterilization step. In general, it is set at on the order of3 to 60 minutes. Some sorts of sterilization apparatuses can be set aton the order of 100 minutes.

[0074] The pressure in a sterilization chamber during this step isgenerally set at on the order of +0.2 MPa relative to atmosphericpressure.

[0075] Next, the high-pressure steam sterilization step of the endoscopein general prevacuum type will be described briefly.

[0076] The endoscope 2, which is a target apparatus for sterilizationand in which the waterproof cap 33 is fitted to the electric connectorportion 11, is contained in the container case 34 for sterilization, andis placed in the sterilization chamber. By fitting the waterproof cap 33to the aforementioned electric connector portion 11, the pressurecontrol valve becomes in the condition of being closed and, therefore,the aforementioned vent holes are blocked. That is, the inside of theendoscope 2 and the outside are closed with watertightness.Subsequently, the inside of the sterilization chamber before thehigh-pressure steam sterilization step is made to be in the condition ofreduced pressure (prevacuum step).

[0077] This prevacuum step is a step for making steam penetrate intodetail of the target apparatus for sterilization during thesterilization step, and by reducing the pressure in the sterilizationchamber, high-pressure high-temperature steam goes throughout the targetapparatus for sterilization. In general, the pressure in thesterilization chamber during this prevacuum step is set at on the orderof −0.07 to −0.09 MPa relative to atmospheric pressure.

[0078] However, when the pressure in the sterilization chamber isreduced during the prevacuum step, the external pressure becomes lowerthan the internal pressure of the endoscope 2 and, therefore, pressuredifference occurs. Then, the pressure control valve of theaforementioned waterproof cap 33 is opened and, therefore, the inside ofthe endoscope 2 and the outside become in the condition of beingcommunicated with the aforementioned vent holes therebetween. Accordingto this, occurrence of a large pressure difference is prevented. Thatis, it is prevented that the endoscope 2 is broken due to the pressuredifference between the internal pressure and the external pressure.

[0079] Subsequently, high-pressure high-temperature steam is suppliedinto the sterilization chamber and, therefore, sterilization isperformed (sterilization step).

[0080] In this sterilization step, the inside of the sterilizationchamber is pressurized. Then, such a pressure difference that theexternal pressure becomes higher than the internal pressure of theendoscope 2 occurs. Consequently, the pressure control valve of theaforementioned waterproof cap 33 is closed and, therefore, penetrationof high-pressure steam into the inside of the endoscope through the ventholes is interrupted.

[0081] However, the high-pressure steam passes through the integumentlayer 39 of the aforementioned pliable tube 15 formed from amacromolecular material, an O-ring which is a seal device installed atthe joint portion of the outer sheath material of the endoscope 2 andwhich is formed from fluororubber, silicon rubber, etc., and the likeand, therefore, gradually penetrates into the inside of the endoscope.

[0082] At this time, the outer sheath material of the endoscope 2becomes in the condition that a pressure has been generated, in whichthe pressure reduced in the prevacuum step and the pressure increased inthe sterilization step are added and which trends from the outsidetoward the inside.

[0083] Subsequently, after the sterilization step is completed, in orderto dry the target apparatus for sterilization after sterilization, theinside of the sterilization chamber is made to be in the reducedpressure condition again and, therefore, drying (drying step) isperformed. In this drying step, the pressure in the sterilizationchamber is reduced, the steam is removed from the inside of thesterilization chamber and, therefore, drying of the target apparatus forsterilization in the sterilization chamber is accelerated. In general,the pressure in the sterilization chamber during this drying step is setat on the order of −0.07 MPa to −0.09 MPa relative to atmosphericpressure. The aforementioned drying step is performed arbitrarily ifnecessary.

[0084] In the pressure reduction step after the sterilization step, thepressure in the sterilization chamber is reduced, the external pressurebecomes lower than the internal pressure of the endoscope 2 and,therefore, pressure difference occurs. When this pressure differenceoccurs, at nearly the same time, the pressure control valve of theaforementioned waterproof cap 33 is opened and, therefore, the inside ofthe endoscope 2 and the outside become in the condition of beingcommunicated with the vent holes therebetween. According to this,occurrence of a large pressure difference between the inside of theendoscope and the outside is prevented. When the pressure reduction stepis completed, the inside of the sterilization chamber is pressurizedand, therefore, such a pressure difference that the external pressurebecomes higher than the internal pressure of the endoscope 2 occurs, thepressure control valve of the aforementioned waterproof cap 33 isclosed.

[0085] When all steps of high-pressure steam sterilization arecompleted, the outer sheath material of the endoscope 2 becomes in thecondition that a pressure, which is the pressure reduced in the pressurereduction step and which trends from the outside toward the inside, hasbeen generated. Thereafter, by removing the waterproof cap 33 from theelectric connector portion 11, the inside of the endoscope 2 and theoutside are communicated through the aforementioned vent holes and,therefore, the inside of the endoscope 2 becomes at atmosphericpressure, and the load due to the pressure difference which has beenbrought about in the outer sheath material of the endoscope 2 iseliminated.

[0086] When the endoscope 2 configured as described above is sterilizedrepeatedly by high-pressure steam sterilization, the gas supply tube 43,water supply tube 44, and endo-therapy product tube 45 contract by X1,X2, and X3, respectively, due to thermal loads.

[0087] On the other hand, when the thermal load of high-pressure steamsterilization is applied to the aforementioned pliable tube 15, thetemperature of the integument layer 39 becomes equivalent to or morethan the thermal deformation temperature and, therefore, it becomespossible to thermally deform. Consequently, as shown in FIG. 7D, thepliable tube 15 is deformed in the direction of contraction of theintegument layer 39 and, in addition, the helical tube 37 and themesh-shaped tube 38 are also deformed in the direction of contraction.At this time, since the helical tube 37 and the mesh-shaped tube 38 areincorporated while being extended by Z (≧Y) compared with being in thenatural length conditions, the aforementioned pliable tube 15 contractsby Y as a whole.

[0088] Since the relationships Y≧X1, Y≧X2, and Y≧X3 are set betweenrespective amounts of contraction X1, X2, and X3 of these tubes 43, 44,and 45 and the amount of contraction Y of the pliable tube 15, even whenthe tubes 43, 44, and 45 contract, the aforementioned pliable tube 15contracts by an amount equivalent to or more than those of the tubes 43,44, and 45. Consequently, it is prevented that the length dimensions ofthe aforementioned gas supply tube 43, water supply tube 44, andendo-therapy product tube 45 become relatively small relative to thepliable tube 15 fixed indirectly and, therefore, the tubes become alwaysin the condition of being sagged.

[0089] As described above, by setting the predetermined relationshipbetween the amount of contraction of the pliable tube and the amounts ofcontraction of the tubes installed while being inserted through theinsertion portion, when high-pressure steam sterilization is performedrepeatedly, the tubes installed while being inserted through theinsertion portion can be prevented from being pulled.

[0090] According to this, problems in that excessive forces are appliedto the joint portions fixing end portions of these tubes, tubes arebroken due to fatigue, inconvenience occurs in the shape of the curvedportion during curving operation, the amount of control force isincreased, and the like are overcome.

[0091] Since it can be prevented that the amounts of sagging of the gassupply tube 43, water supply tube 44, and endo-therapy product tube 45relative to the pliable tube fixed indirectly become smaller thanpredetermined values, in curving operation or in the condition that thepliable tube is curved, these gas supply tube 43, water supply tube 44,and endo-therapy product tube 45 are moved freely in the pliable tubeand, therefore, it is prevented that the light guide, electric cables,etc., are broken due to pressure.

[0092] According to these, durability of the built-in materials of theendoscope is improved and, in addition, operational ease of theendoscope is improved.

[0093] Furthermore, the pliable tube 15 may be formed as shown in FIG.8A to FIG. 8D.

[0094] When the aforementioned pliable tube 15 is assembled, as shown inFIG. 8A, an assembly 50 is formed, in which the helical tube 37 andmesh-shaped tube 38 are combined. As shown in FIG. 8B, a molten resinfor forming the integument layer 39 is extruded while this assembly 50is a core material and, therefore, the assembly 50 is covered.

[0095] Subsequently, while the aforementioned integument layer 39 iscooled and is solidified completely, a tensile force is applied to theassembly 50 covered with the integument layer 39 in the axis direction,the assembly 50 is extended by Z (≧Y) compared with being in the naturallength conditions, and is held. According to this, by curing theintegument layer 39, a desired pliable tube 15 is formed in which theassembly 50 extended by Z compared with being in the natural lengthconditions is covered with the integument layer 39 as shown in FIG. 8C.

[0096] When the thermal load of high-pressure steam sterilization isapplied to the pliable tube 15 thus formed, the temperature of theintegument layer 39 becomes equivalent to or more than the thermaldeformation temperature and, therefore, it becomes possible to deform.Consequently, the helical tube 37, the mesh-shaped tube 38, and theintegument layer 39, which have been incorporated while being extendedcompared with being in the natural length conditions, contract and,therefore, the pliable tube 15 contracts by Y as a whole.

[0097] By thus forming the pliable tube, when the pliable tubecontracts, since the amount of contraction of the integument layerrelative to the natural length conditions is small compared with that inthe aforementioned method, a compressive stress applied to the inside ofthe integument layer can be reduced and, therefore, durability of theintegument layer, that is, the pliable tube, can be improved.

[0098] Any one of or all of the aforementioned gas supply tube 43, watersupply tube 44, and endo-therapy product tube 45 may be subjected to anannealing treatment in advance of assembling at a temperature at which athermal road is similar to the thermal road in the high-pressure steamsterilization step and, therefore, may contract by a specified amount.According to this, the absolute values of the amounts of contraction X1,X2, and X3 become small, the range of the amount of contraction Y isincreased and, therefore, flexibility in selection of the material,structure, and manufacturing method of the pliable tube 15 is increased.In addition, since the amount of contraction Y can also be reduced, theamount of change between at the initial condition and at high-pressuresteam sterilization becomes small.

[0099] Contrary to the above description, the pliable tube 15 may beannealed in advance and, therefore, may contract by a specified amountwithin the range of the number of endurance examples of the endoscope 2against high-pressure steam sterilization and within the rangesatisfying the relationships Y≧X1, Y≧X2, and Y≧X3.

[0100] Next, an embodiment related to an endoscope, in which even whenhigh-pressure steam sterilization is performed repeatedly, it isprevented that the inner diameter of the pliable tube is changed in thedirection of contraction and inconvenience occurs in the built-inmaterials, that is, the inner diameter dimension remains in thecondition as it is or becomes in the condition that the diameter isenlarged, will be described.

[0101] In the present embodiment, the pliable tube is formed in orderthat when the pliable tube 15 is applied with the thermal load duringhigh-pressure steam sterilization and, thereafter, is returned toambient temperature, the inner diameter becomes equivalent to or morethan the inner diameter before application of the thermal load.

[0102] The configuration of a pliable tube according to the presentembodiment will be described with reference to FIG. 9A and FIG. 9B whichare diagrams for explaining the configuration of the pliable tube.

[0103] Regarding the pliable tube 15A according to the presentembodiment, since the helical tube 37 and the mesh-shaped tube 38 areextended during the manufacturing step compared with being in thenatural length conditions as described above, the inner diameterdimension has been reduced compared with that in the natural conditionbecause of the structure thereof. That is, as shown in FIG. 9A and FIG.9B, in the pliable tube formation conditions, the aforementioned helicaltube 37 and the mesh-shaped tube 38 are integrated with the integumentlayer 39 while being in the condition that the diameter is reduced to φd(FIG. 9B) smaller than φD (FIG. 9A) which is the inner diameter in thenatural length conditions, and that condition is maintained and fixed.

[0104] Consequently, when the thermal load of high-pressure steamsterilization is applied to the pliable tube 15, the temperature of theintegument layer 39 becomes equivalent to or more than the thermaldeformation temperature and, therefore, it becomes possible to deform.Regarding this sterilization step of high-pressure steam sterilization,a pressure of about 0.2 MPa is applied in the gravity type sterilizationapparatus and a pressure of about 0.3 MPa is applied in the prevacuumtype sterilization apparatus from the external side to the internal sideof the pliable tube 15 and, therefore, a force is exerted in thedirection of diameter reduction of the aforementioned pliable tube 15.

[0105] However, in the helical tube 37 and mesh-shaped tube 38incorporated while the diameters have been reduced relative to thenatural condition, since the force in the direction of diameterincrease, which is a force tending to return to the natural condition,is always exerted, this force opposes the aforementioned force in thedirection of diameter reduction and, therefore, the inner diameter isnot reduced by a large degree in the aforementioned pressurizedcondition. In addition, when the aforementioned pressurized condition iscompleted, only the force in the direction of diameter increase isexerted on the helical tube 37 and mesh-shaped tube 38, and when thepliable tube 15 is cooled, the integument layer 39 becomes unable todeform. That is, the helical tube 37, mesh-shaped tube 38, and theintegument layer 39 are fixed while being in this condition.

[0106] At this time, the inner diameters of the helical tube 37 andmesh-shaped tube 38 are kept and fixed to be equivalent to or more thanthe inner diameter before application of the thermal load of thehigh-pressure steam sterilization step although these vary depending onthe cooling speed of the aforementioned integument layer 39.Consequently, the inner diameter dimension of the pliable tube 15 atambient temperature after application of the thermal load of thehigh-pressure steam sterilization step becomes equivalent to or morethan the inner diameter dimension at ambient temperature beforeapplication of the thermal load.

[0107] In the case of a prevacuum type sterilization step, since thepressure in the endoscope is generally kept in the condition of reducedpressure on the order of −0.09 MPa when the step is completed, it isdesirable that the pliable tube 15 is formed while the diameters of thehelical tube 37 and mesh-shaped tube 38 are reduced in order that aforce of about 0.09 MPa or more is exerted on the helical tube 37 andmesh-shaped tube 38 in the direction of diameter increase.

[0108] Furthermore, in consideration of deformation in the pressurizedcondition, it is most reliable that the pliable tube 15 is formed inorder that a force of +0.2 MPa during pressuring in the gravity type orabout 0.29 MPa (0.2+0.09) or more in the prevacuum type in considerationof pressure difference between during pressuring and during pressurereduction is exerted in the direction of diameter increase.

[0109] As described above, by extending the helical tube and mesh-shapedtube compared with being in the natural length conditions in advanceduring the manufacturing step, since these helical tube and mesh-shapedtube are incorporated while the diameters are reduced relative to thatin the natural condition, a force is always exerted in the direction ofdiameter increase during high-pressure steam sterilization and,therefore, it is prevented with reliability that the inner diameter ofthe pliable tube becomes equivalent to or less than the inner diameterdimension at ambient temperature.

[0110] According to this, when high-pressure steam sterilization isperformed repeatedly, it is prevented that the inner diameter of thepliable tube is reduced and, therefore, the built-in light guide,electric cables, and pipeline tubes are broken due to pressure.

[0111] Since an increase in filling factor of the built-in materials inthe insertion portion is prevented, a proper clearance is kept and,therefore, the built-in materials can move freely in the insertionportion.

[0112] According to these, it is prevented that the inner diameterdimension of the pliable tube contracts and the built-in materials arebroken, and consequently, an endoscope having excellent durability isprovided.

[0113] Furthermore, regarding the pliable tube according to theaforementioned embodiment shown in FIG. 8A to FIG. 8D, in the pliabletube formation conditions, the integument layer, in addition to theaforementioned helical tube and mesh-shaped tube, is extended comparedwith being in the natural length conditions, the inner diameter of theintegument layer is also in the condition of being reduced compared withthe inner diameter in the natural condition and, therefore, similaractions and effects are achieved.

[0114] In the pliable tube formation conditions, the aforementionedhelical tube 37 may be configured to be the same as in the naturallength conditions as shown in FIG. 10A and FIG. 10B which are diagramsfor explaining another configuration of the pliable tube. Specifically,the pliable tube 15B according to the present embodiment has aconfiguration in which in order that the length dimension is set to bethe same as that in the natural length conditions, the interval P1between the adjacent strips is specified to be P2 narrower than theinterval in the natural condition and, in addition, the helical tube 37,in which the inner diameter dimension has been reduced to φd smallerthan the inner diameter φD in the natural condition, is covered with themesh-shaped tube 38 and the integument layer 39.

[0115] By thus configuring the pliable tube 15B, when the thermal loadof high-pressure steam sterilization is applied, the temperature of theintegument layer 39 becomes equivalent to or more than the thermaldeformation temperature and, therefore, it becomes possible to deform.Consequently, an action tending to return to the natural condition isexerted on the helical tube 37. According to this, the inner diameterdimension of the pliable tube 15 at ambient temperature afterapplication of the thermal load of the high-pressure steam sterilizationstep becomes equivalent to or more than the inner diameter dimension atambient temperature before application of the thermal load. However, atthis time, the interval between the adjacent strips is increased and,therefore, the total length is not changed.

[0116] As described above, since the diameter of the helical tube isreduced and the interval between the strips is configured to be a narrowwidth, in addition to the effects of the pliable tube shown in theaforementioned FIG. 9A and FIG. 9B, it can be eliminated that the lengthof the pliable tube contracts due to high-pressure steam sterilization.

[0117] Furthermore, in a manner similar to that in the aforementionedhelical tube, when the length of the mesh-shaped tube is not changedfrom that in the natural length conditions, the interval betweenadjacent knitted thin wires is specified to be smaller than that in thenatural length conditions, and, therefore, the pliable tube isconfigured while the inner diameter is in the condition of beingshrunken compared with that in the natural condition, similar actionsand effects can also be achieved.

[0118] The aforementioned configuration may be used for a multilayerhelical tube configured by combining helical tubes doubly or triply.

[0119] As described above, according to the present invention, theendoscope, in which the inconvenience brought about due to contractionof the tube element built in the insertion portion during high-pressuresteam sterilization is prevented, is provided.

[0120] Having described the preferred embodiments of the inventionreferring to the accompanying drawings, it should be understood that thepresent invention is not limited to those precise embodiments andvarious changes and modifications thereof could be made by one skilledin the art without departing from the spirit or scope of the inventionas defined in the appended claims.

What is claimed is:
 1. An endoscope comprising a pliable tube having anintegument layer made of a resin constituting an insertion portion andat least one slender tube element inserted through the insertionportion, wherein: the amount of contraction of the pliable tube afterapplication of a thermal load during a high-pressure steam sterilizationstep is set larger than the amount of contraction of the tube elementafter the application of the thermal load during the high-pressure steamsterilization step.
 2. The endoscope according to claim 1, wherein: thepliable tube comprises the integument layer and a metal tube installedintegrally on the inner perimeter surface side of this integument layer;the integument layer is formed from a resin having a thermal deformationtemperature equivalent to or less than a temperature applied during thehigh-pressure steam sterilization step; and the metal tube is formed inthe pliable tube formation conditions while being extended compared withbeing in the natural length conditions.
 3. The endoscope according toclaim 2, wherein: the metal tube comprises a helical tube formed from ametal strip and a mesh-shaped tube formed from a thin metal wire; and atleast one of the helical tube and the mesh-shaped tube is formed in thepliable tube formation conditions while being extended compared withbeing in the natural length conditions.
 4. The endoscope according toclaim 1, wherein the integument layer is formed from a resin having athermal deformation temperature equivalent to or less than a temperatureapplied during the high-pressure steam sterilization step, and theintegument layer is formed in the pliable tube formation conditionswhile being extended compared with being in the natural lengthconditions.
 5. The endoscope according to claim 1, wherein the tubeelement is a channel tube of a fluid transportation tube fortransporting a fluid or of an endo-therapy product insertion channel. 6.The endoscope according to claim 1, wherein the integument layer of thepliable tube is formed from any one of ester-based thermoplasticelastomer, amide-based thermoplastic elastomer, styrene-based resin,fluorine-based rubber, and silicon-based rubber, or a resin member madeby blending them.
 7. A manufacturing method for an endoscope providedwith a pliable tube comprising an integument layer formed from a resinand a metal tube fitted integrally into this integument layer in aninsertion portion, comprising the steps of: extending the metal tube bya predetermined amount compared with the length in the natural lengthconditions; and forming the integument layer around the metal tubeextended, wherein the predetermined amount is larger than the amount ofcontraction of the pliable tube due to high-pressure steamsterilization.
 8. The manufacturing method according to claim 7, whereinthe step of forming the integument layer is a step of forming theintegument layer by extruding a molten resin around the metal tubeextended.
 9. The manufacturing method according to claim 7, wherein thestep of forming the integument layer is a step of forming the integumentlayer by applying a covering of tube element made of a resin to becomethe integument layer around the metal tube extended.
 10. A manufacturingmethod for an endoscope provided with a pliable tube comprising anintegument layer formed from a resin and a metal tube fitted integrallyinto this integument layer in an insertion portion, comprising the stepsof: forming the pliable tube by forming the integument layer byextruding a molten resin around the metal tube; and extending thepliable tube by a predetermined amount compared with the length in thenatural length conditions by applying a tensile force in the axisdirection during solidification of the resin, wherein the predeterminedamount is larger than the amount of contraction of the pliable tube dueto high-pressure steam sterilization.